(1.) Field of the Invention
The present invention relates to a process and apparatus for manufacturing fasciated spun yarns by utilizing the open end spinning method.
(2.) Description of the Prior Art
As methods for the production of yarns of this type, there have been proposed a method in which, as disclosed in Japanese Unexamined Patent Publication No. 52-37837, the accumulation width of a fiber-collecting portion of a rotor is expanded, separated single fibers are supplied toward the inner wall-face of the rotor, the fibers are collected in the fiber-collecting portion by a centrifugal force due to rotation of the rotor, true twists are applied to the collected fibers by rotation of the rotor when the collected fibers are taken out by a delivery roller, and false twists are simultaneously applied to the collected fibers by a pneumatic false-twisting nozzle, and also a method in which, as disclosed in Japanese Unexamined Patent Publication No. 58-109630, separated single fibers are supplied to the inner-face of a drum rotor and deposited on an accumulation surface, a bundle of the deposited fibers is taken out and twisted by guide means rotated at a higher speed than that of the drum rotor, a deflector is engaged with the fiber bundle between the accumulation surface and guide means to broaden the width of the fiber bundle, and the broadened fiber bundle is false-twisted by a pneumatic false-twisting nozzle. However, these methods involve unsolved problems, in that in the former method, the width of the bundle of the deposited fibers is broaden so as to create a difference of the applied twists between the inner and outer layers of the fiber bundle, fluffs are created by this difference of the applied twists, and these fluffs are entwined around the twisted yarn by release of the false twists to form a fasciated yarn. Accordingly, it is difficult to uniformly deposit single fibers along the entire width of the accumulation surface, and a sufficient number of fluffs cannot be produced on the surface of the twisted yarn. Furthermore, as soon as fluffs are produced, the fluffs are entwined on the periphery of the twisted yarn, and the difference of the applied twists between the false-twisted fibers and the fluffs is reduced, with the result that fasciation twisting of the fluffs by untwisting is reduced and the fasciation effect is lowered. As a result of our experiments, it was found that even if a fasciated spun yarn is formed according to this method, the number of fasciated fibers is small and the strength of the yarn is very low. The pneumatic false twisting nozzle utilized for the former method is provided with a yarn passage aperture formed along the entire length thereof wherein the inside diameter of this aperture is uniform, and a jet aperture opened rectangular to the axis of the yarn passing aperture which is directed to the outlet of the yarn passing aperture, while the projection of the axis of the jet aperture on a plan perpendicular to the axis of the yarn passing aperture is tangent to the projection of the inside wall of the yarn passing aperture onto a plan perpendicular to the axis of the yarn passing aperture. Therefore, when compressed air is ejected from the jet aperture into the yarn passing aperture, a swirling jet stream is created along the inside wall of the yarn passing aperture so that false twists are applied to the fiber bundle passing through the yarn passing aperture, while a suction air stream from the inlet to the outlet of the yarn passing aperture is created so that a pulling tension toward the outlet of the yarn passing aperture is created. In the method utilizing such a pneumatic false twisting nozzle, where the twisted yarn is false-twisted by passing the twisted yarn taken out from the rotating rotor into a yarn passing aperture of a pneumatic false-twisting nozzle as described above, since the force of holding the top end of the yarn on the fiber-collecting portion of the rotor is weak, there is a risk that the twisted yarn is pulled out from the rotating rotor by a tension generated in the taking-out direction by a jetted air stream, and hence, sufficient false twist cannot be imparted to the twisted yarn. In the above-mentioned conventional pneumatic false-twisting nozzle, a swirling air current is produced in the yarn-passing aperture having a uniform diameter so as to apply false twists. Accordingly, even if the jetting direction of a jet aperture is made rectangular to the axis of the yarn passing aperture, it is difficult to apply sufficient false twists to the twisted yarn and it also is difficult to increase the spinning speed or the yarn strength. In the latter method, since the bundle of fibers deposited on the accumulation surface of the drum rotor is taken out while guiding by the guide means rotated at a high speed, it is difficult to control the difference of the rotation speed between the drum rotor and guide means so as to fit the yarn take-out speed, and moreover, thickness-unevenness is readily caused in the obtained fasciated spun yarn. Furthermore, a very complicated apparatus is required for carrying out this method, and hence, this method is not preferred from a practical viewpoint.